import SimplePrelude hiding ((.), curry, uncurry, const)

----------------------------------------------------------------------------
-- Composition function:
(.) :: (b -> c) -> (a -> b) -> (a -> c)
f . g = \x -> f (g x)

ex1 :: String -> Int
ex1 = sum . filter (\n -> n>=65 && n<=90) . map ord

curry :: ((a,b) -> c) -> a -> b -> c
curry f x y = f (x,y)

uncurry :: (a -> b -> c) -> (a,b) -> c
uncurry f (x,y) = f x y

-- Multiplies the pairwise sum of two lists:
ex2 :: [Int] -> [Int] -> Int
ex2 xs ys = prod (map (uncurry (+)) (zip xs ys))
  where prod = foldr (*) 1

-- The always constant function
const :: a -> b -> a
const x _ = x